1. The Field of the Invention
This invention relates to apparatus, methods and systems for grinding, cleaning and drying brittle recyclable materials such as glass. More particularly, the invention relates to processing contaminated post consumer waste recyclable materials and turning it into a clean and dry usable raw material.
2. The Prior State of the Art
In order for recycled glass to be used as a raw material in such high end products as fiberglass it must be 99.9% free of contaminants, and dry. The only benefication plants that come close to doing this cost up to $3 million dollars to build. Other less expensive systems, such as those sold under the names Enviro Mill and Andelah for about $100,000, fail to yield a product which is anywhere near 99.9% clean.
At the present time, most glass is being recycled back into the container industry. Why? Because a container manufacturer can purchase enough recycled glass to cover the costs of building an expensive benefication plant.
A glass container is 100% recyclable and can be recycled over and over again with no loss in quality of purity, the drawback being that the glass must be sorted by colors, the industry using a majority of flint, 60%, then amber, 23%, then green, 13%.
The fiberglass industry, along with other emerging industries, can use large quantities of broken mixed glass (glass that is not sorted), but the glass must be 99.9% contaminant free. Even most of the current benefication plants fail to meet these standards.
The reason these industries are seeking clean sources of recycled glass is because glass melts at a lower temperature than the normal raw materials used to make glass allowing the manufacturing company to lower its energy costs while at the same time increasing the life of its equipment. In a normal melting furnace, for every 10% of recycled glass used, there is approximately a 2.5% reduction in energy used.
Approximately 80% of all post consumer bottle waste glass is now being recycled back into glass containers. Thus, this is where processors of post consumer waste glass have focused their efforts. These processors have relied on technology which although adequately providing the container industry with a usable raw material, the material is not clean enough to be used as a feed stock for other high end uses such as fiberglass.
In the past few years, because other industries such as the fiberglass industry have begun to seek sources of recycled glass, significant resources have been invested in trying to improve glass recycling. Innovations include automated color separation, mechanized ceramic sorting, organic color coating and attempts at improving grinding technologies. However, in most cases, all this state-of-the-art processing equipment has managed to do is increase the cost of recycled glass, making it even more uneconomical for high end-users to use recycled glass as a substitute raw material.
Most processing systems grind the glass in the same chamber with the contaminants making the recycled glass usable only for such low end uses as landfill, glassphalt, and as a trench bedding material for piping. These systems do allow communities to recycle this waste glass, keeping it out of the landfill and from polluting the environment, but at a high economical cost.
Transportation costs are also a major obstacle to the use of recycled glass. If a high end-user of recycled glass is not located in the immediate area of a community, most end up dropping glass from their recycling program simply because they cannot afford the economic drain.
Accordingly, there is a need for improved apparatus, methods and systems for grinding and cleaning glass that overcome or avoid the above problems.